针对锂离子电池负极连接片多层结构工艺复杂、成本高的问题，本文提出单层结构优化方案，通过硬度调控提升工艺适配性。设计了三种硬度区间（35.2～36.3 HV、36.6～37.9 HV、38.1～40.2 HV）的单层连接片，经产线验证优选出最佳硬度范围，并从焊接质量、短路率、交流内阻、倍率充放电性能、温升特性以及振动可靠性等维度进行系统性实验评估，与多层结构历史数据对比分析。结果表明：硬度36.6～37.9 HV的单层连接片超声波焊接后形态稳定，整形工序不良率由多层结构的约4.5%～6%降至1.2%；超声波焊接焊印残留率达100%，激光焊接有效熔深、有效熔宽平均值分别为0.415 mm和1.204 mm，基材本体及焊线载流能力均满足230 A过流能力的设计要求，剥离测试表现为母材断裂，焊线强度高于母材本身；归因于连接片的短路率稳定控制在≤0.11%，较多层结构降低约50%；单层结构电池交流内阻（ACR）均值（0.2939 mΩ）与多层结构（0.2935 mΩ）基本持平（P=0.343），倍率充放电容量保持率≥99.4%，温升特性相当，振动测试过程中电压与温度均无异常波动，连接可靠性良好。该方案简化工艺、降低成本，关键产线指标优于多层结构，为锂离子电池连接片的结构优化提供了工程参考。

To address the issues of complex manufacturing process and high cost of multi-layer negative electrode tabs in lithium-ion batteries， this paper proposes a single-layer structural optimization scheme that enhances process adaptability through hardness control. Three hardness ranges (35.2–36.3 HV， 36.6–37.9 HV， and 38.1–40.2 HV) of single-layer tabs were designed， and the optimal hardness range was selected through production line validation. The optimized scheme was systematically evaluated in terms of welding quality， short circuit rate， alternating current internal resistance (ACR)， rate charge–discharge performance， temperature rise characteristics， and vibration reliability with comparative analysis against historical data of multi-layer structures. The results indicate that single-layer tabs with a hardness of 36.6–37.9 HV exhibit stable morphology after ultrasonic welding， and the shaping process defect rate decreased from approximately 4.5%–6% (multi-layer structure) to 1.2%. The ultrasonic welding mark retention rate reached 100%， and the average effective penetration depth and width of laser welding were 0.415 mm and 1.204 mm， respectively， meeting the design requirement of 230 A current-carrying capacity for both the base metal and the weld line. The peel test exhibited base metal fracture， indicating that the weld strength is higher than that of the base metal itself. The short circuit rate attributable to the tab itself was stably controlled at ≤0.11%， representing a reduction of approximately 50% compared with the multi-layer structure. The mean ACR of the single-layer structure (0.2939 mΩ) was comparable to that of the multi-layer structure (0.2935 mΩ) with no significant difference (P=0.343). The optimized cells achieved a capacity retention rate of ≥99.4% in rate charge–discharge tests， with temperature rise characteristics comparable to those of the multi-layer structure. During vibration testing， no abnormal fluctuations in voltage and temperature were observed， demonstrating good connection reliability. This scheme simplifies the manufacturing process， reduces costs， and outperforms the multi-layer structure in key production line indicators， providing an engineering reference for the structural optimization of lithium-ion battery tabs.